The present invention relates generally to an apparatus for unloading bulk materials from containers, and more specifically relates to an apparatus for use in unloading bulk material from containers having at least one discharge outlet at an elevation spaced above the apparatus, where the apparatus is vertically adjustable to engage the discharge outlet.
Many bulk-carrying containers, such as railroad hopper cars, typically contain on a funnel-shaped discharge outlet or “hopper” on an underside so that bulk cargo, such as, for example, grain, cement powder, fly ash and coal, can be quickly discharged through the underside. Thus, an apparatus for receiving the bulk cargo as it is discharged through the hopper is necessary to collect and channel the bulk cargo as it is discharged. To this end, attempts have been made to provide an apparatus that connects to the hopper at the underside of the bulk-carrying containers that receive the bulk cargo as it is discharged and channel the bulk cargo to a desired location, such as a storage tank, transport vehicle, silo, or the like. These previous attempts have typically involved apparatuses that incorporate a four-bar linkage design to lift a top frame to the hopper. Such four-bar linkage systems include sliding surfaces and pins that may be easily fouled by bulk cargo or other debris, causing binding in the system and ultimately failure of the system to operate.
Moreover, the coupling between the previous apparatuses and the hopper is frequently unstable. Four-bar linkage systems typically require the top frame to be parallel to the bottom frame, which is generally parallel with the ground surface upon which it rests. The top frame must therefore remain level with the grade of the ground surface underneath the hopper, while the hopper itself may not be level with grade. Thus, coupling between previous apparatuses and the hopper is unstable.
Furthermore, apparatuses incorporating the four-bar linkage system have limited lifting ability, especially at low positions, because the four-bar linkage typically requires some mechanical advantage before the drive actuator can effectively transfer its force to lift the top frame. With a 4-bar linkage, at low levels, the actuator provides enough force to lift the mechanism, but the actuator is nearly horizontal, and therefore has very little lifting force directed vertically. This results in an inability to seal well or provide enough lifting force to mate properly at lower height levels.
Thus, while unloading apparatuses have been available for many years, the manner in which they are lifted, aligned with, and coupled to the hopper has been the subject of continuing efforts to provide a simple and effective mechanism for providing an improved lifting mechanism for lifting the unloading apparatus to the hopper, maintaining adequate coupling of the apparatus to the hopper, and for preventing disengagement of the unloading apparatus from the hopper.